With the development of the communication technology, people have put forward the increasingly high demand for the capacity of the communication system, and in the next several years, the demand for the system capacity will be doubled and redoubled. On one hand, it is difficult for the high order modulation and the high coding rate to confront the influence caused by the channel fading in the wireless transmission, and on the other hand, although the application of the multi-antenna technology can make the transmission capacity of the system increase exponentially, it puts forward much higher demand for the complexity of the communication device at the same time. Especially in the system of the fast varying channel, the feedback of the User Equipment (UE) often fails because of the factor, such as, the time delay, etc., and in this case it can only be solved by the open loop technology.
The open loop transmission technology involved in the Long Term Evolution/Long Term Evolution-Advanced (LTE/LTE-A) at present mainly includes the open loop diversity and the open loop pre-coding technology. The open loop diversity technology can better confront the channel fading, but in order to obtain the high diversity gain effect, it is often got in return by sacrificing the transmission efficiency, so it is unable to meet the demand of the system capacity. While for the transmission mode of the Bell Labs layered Space-Time (BLAST), on one hand, the characteristic of the channel is not considered, and the number of the receiving antennas is required to be greater than or equal to the number of the transmitting antennas, and under the relevant channel, the correlation of the channel will cause the serious interference produced among different data flows (or different layers) in different transmitting antennas. Although the open loop pre-coding technology can realize the parallel transmission of multiple data flows (or multiple layers) and it can realize dynamically adjusting the number of the transmitted data flows (or layers) according to the characteristic of the channel, and the pre-coding weight is polling used by a preset mode or obtained by a random selection mode, and the characteristic of the channel cannot be efficiently used.
Another transmission technology put forward in recent years is the space modulation technology, and its basic principle is to dynamically select the transmitting antenna according to the bit information to be transmitted, thus utilizing different transmitting antennas to transmit certain data information, however, the described scheme is only suitable for the transmission of single data flow (layer), and the whole efficiency of the open loop Multiple-Input Multiple-Output (MIMO) system cannot be fully developed.